This new finding adds to growing evidence of the painkilling potential of cannabis. Animal research has shown that cannabinoids can decrease pain sensation caused by inflammation, damaged nerves, and cancer. Also, studies have pointed to cannabinoids as helping control pain from muscle spasticity -- muscle stiffness and limb rigidity -- in patients with multiple sclerosis (MS).
There are many different types of pain that a person with multiple sclerosis sufferers. The list includes pain caused by plaque lesions seen in the brains of people with multiple sclerosis called central pain. These lesions may cause pain by altering chemicals which transmit pain signals or they may cause changes in the way signals are transmitted to pain regions in the brain.
Can cannabis relieve central pain in multiple sclerosis patients with lesions? This is the first study examining that question -- and it shows a "modest but relevant" reduction in pain, writes researcher Kristina B. Svendsen, MD, with the Danish Pain Research Center and department of neurology at Aarhus University Hospital in Denmark. Her study appears in this week's issue of the British Medical Journal.
In Svendsen's study, the 24 multiple sclerosis patients with central pain took capsules containing dronabinol, a cannabis extract, or a placebo capsule for three weeks. In the study, central pain was pain in a body area that led to abnormal sensation when subjected to a pinprick, touch, or changes in temperature. The patients also recorded their pain intensity.
Those taking the cannabis extract had significantly lower pain intensity -- and greater pain relief -- compared with patients taking the placebo, she reports. They also had less pressure-related pain and better mental health. The greatest pain relief came during the last week of their treatment.
It's possible that some pain reduction was related to fewer spasms, she notes. Also, some of the mental health benefits may have been caused by the generalized pain relief. Despite these positive findings she does report that functionally these patients did not change.
The most common side effects were dizziness, headache, fatigue, and muscle aches, reports Svendsen. However, no patients withdrew from the study because of these side effects. Also, in the last week of treatment, there were fewer side effects -- indicating that patients adapted to the drug over time.
SOURCE: Svendsen, K. British Medical Journal Online First, July 17, 2004.